Computer simulation has been heavily and fruitfully used to predict qualitatively the behavior of chemically interacting macromolecules during transport experiments. It is proposed to use numerical modelling of the velocity sedimentation of self-associating solutes in the ultracentrifuge to define the chemical equilibria quantiatively in terms of reaction stoichiometry and equilibrium constants. The project will have three specific objectives: 1. Simulated experiments will be used to consider how nearly unique the boundary shape is for a particular self-associating system. Simulations will be done for various model reactions, and all of the system parameters will be adjusted within physically plausible ranges to make the calculated boundaries given by different models resemble each other as closely as possible. 2. Model calculations will be done to fit experimental sedimentation velocity profiles for bovine liver glutamate dehydrogenase. This solute will be assumed to undergo a self-association reaction of the linear indefinite type, as already shown in other laboratories by light scattering, equilibrium sedimentation and gel chromatography. 3. Experimental and simulated sedimentation velocity profiles will be used along with equilibrium sedimentation to define the self-association equilibrium shown by the major component of the hemoglobin of the bullfrog tadpole (Rana catesbeiana).